This is honestly one of my favorite romcoms right now.
-The main relationship is already underway, so there's no will they/won't they stalling that is so common in the genre.
-The girls in the harem all like each other, so when they bicker its like friends rather than rivals. It's fun! Heck, we even see in a flashback (Chapter 9) Reina says she, Yukina, and Ruri will be together forever long before Imaizumi entered their lives.
-there are some actual stakes with keeping the relationship secret (ie, it might end), and slowly more side characters are coming under Ruri's influence to help keep it under wraps
-Keita is cute cute cute.
I'm so glad Norigorou is able to tell more stories with these characters beyond "they have lots of sex" and I really hope this gets more popular.